Conventionally, a compressor includes a first muffler chamber communicating with a first cylinder chamber, a second muffler chamber communicating with a second cylinder chamber, a gas passage for making the first muffler chamber and the second muffler chamber communicated with each other, and a Helmholtz type resonance chamber. A vertically intermediate portion of the resonance chamber and the gas passage are connected to each other by a connecting passage (see, e.g., JP 7-247974 A).
However, in the conventional compressor, since the connecting passage is connected to the vertically intermediate portion of the resonance chamber, oil contained in refrigerant gas may enter into the resonance chamber to accumulate in the resonance chamber, disadvantageously. This accumulation of oil in the resonance chamber would cause the resonance chamber to change in capacity, causing the frequency of damping noise (pulsation noise) to change, which leads to a degraded muffling effect as a problem.